I am developping a Qlik Sense App and I need to to do a Nth degree polynomial trendline.
During my research, I have found that QlikView have a Trendline section that does not seems to exist in Qlik Sense. There is also this topic about making formula to calculate trend line in Qlik Sense that was created in 2017 :
Qlik doesn't offer this and probably won't offer this because it's a statistics part.. less a BI part. You can use the Vizlib Line Chart, it contains a polynomial function for a trendline. But you can't edit this formula.
QlikView is also a BI tools and has the functionnality to create trend line, I think it is still possible that Qlik implements a section for trend lines in Qlik Sense.
In any case, thanks for proposing the extension Vizlib but I would not be able to use it because my companie does not use extension in their apps. I will try to figure out a formula using the python back-end.